PDL-2.007

NAME

PDL::Fit::LM -- Levenberg-Marquardt fitting routine for PDL

DESCRIPTION

This module provides fitting functions for PDL. Currently, only Levenberg-Marquardt fitting is implemented. Other procedures should be added as required. For a fairly concise overview on fitting see Numerical Recipes, chapter 15 "Modeling of data".

In scalar context returns a vector of the fitted dependent variable. In list context returns fitted y-values, vector of fitted parameters, an estimate of the covariance matrix (as an indicator of goodness of fit) and number of iterations performed.

An extended example script that uses lmfit is included below. This nice example was provided by John Gehman and should help you to master the initial hurdles. It can also be found in the Example/Fit directory.

a threaded version of lmfit by using perl threading. Direct threading in lmfit seemed difficult since we have an if condition in the iteration. In principle that can be worked around by using where but .... Send a threaded lmfit version if you work it out!

Since we are using perl threading here speed is not really great but it is just convenient to have a threaded version for many applications (no explicit for-loops required, etc). Suffers from some of the current limitations of perl level threading.

BUGS

Not known yet.

AUTHOR

This file copyright (C) 1999, Christian Soeller (c.soeller@auckland.ac.nz). All rights reserved. There is no warranty. You are allowed to redistribute this software documentation under certain conditions. For details, see the file COPYING in the PDL distribution. If this file is separated from the PDL distribution, the copyright notice should be included in the file.